Issued  October  28, 1911. 


U.  S.  DEPARTMENT  OF  AGRICULTURE. 


FARMERS'    BULLETIN  467. 


THE  CONTROL  OF  THE  CHESTNUT 

BARK    DISEASl-.IBRARY  of  the 

MaLQ^aLctitJisett^ 

^griciiltij.ra  ] 

Colleg^'e. 


HAVEN  METCALF, 

Pathologist  in  Charge,  Investigations  in  Forest  Pathology, 

AND 

J.  FRANKLIN  COLLINS, 

Forest  Pathologist,  Investigations  in  Forest  Pathology, 
Bureau  of  Plant  Industry . 


WASHINGTON: 

GOVERNMENT   PRINTING  OFFICE. 

1911. 


LETTEE  OF  TEA:r^SMITTAL. 


U.  S.  Department  of  Agriculture, 

Bureau  of  Plant  Industry, 

Office  of  the  Chief, 
Washington^  D.  C,  August  11^^  1911. 
Sir  :  I  have  the  honor  to  transmit  herewith  and  to  recommend  for 
publication  as  a  Farmers'  Bulletin  a  manuscript  entitled  "  The  Con- 
trol of  the  Chestnut  Bark  Disease,"  by  Dr.  Haven  Metcalf,  Patholo- 
gist in  Charge,  and  Prof.  J.  Franklin  Collins,  Forest  Pathologist, 
of  the  Office  of  Investigations  in  Forest  Pathology.  The  writers 
describe  their  method  of  restricting  the  spread  of  this  dangerous 
disease  by  destroying  advance  infections,  a  method  which  is  already 
being  ajDplied  on  a  large  scale  by  the  State  of  Pennsylvania.  It  is 
hoped  to  perfect  plans  whereby  through  general  cooperation  the 
disease  may  be  kept  within  the  territory  where  infection  is  already 
general  and  the  largest  and  best  chestnut  forests  of  the  country, 
especially  those  of  the  south  Appalachians,  be  kept  permanently  free 
from  the  disease. 

The   experimental   data   upon   which   the  recommendations   con- 
tained in  this  publication  are  based  will  be  published  in  full  in  a 
forthcoming  bulletin  of  the  Bureau  of  Plant  Industry. 
Respectfully, 

B.  T.  Galloway, 

Chief  of  Bureau. 
Hon.  James  Wilson, 

Secreta7'y  of  Ag7'iculture. 

467 
2 


OONTElsrTS. 


Page. 

The  disease 5 

History  and  distribution 5 

Financial  losses 5 

Cause  and  symptoms 6 

Means  of  spread  and  entrance 9 

The  control  of  the  disease '     10 

Elimination  and  quarantine 10 

Fundamental  observations  and  experiments 10 

Legal  considerations 11 

The  method  in  detail 12 

Locating  advance  infections  ("scouting") 12 

Destroying  advance  infections 13 

Establishing  the  "immune  zone  " 13 

Quarantine 14 

Program  for  the  second  year 14 

The  example  of  Pennsylvania 14 

Inspection  of  diseased  nursery  stock 17 

Individual  treatment  of  diseased  trees 18 

Advice  to  chestnut  orchardists 20 

Advice  to  owners  of  chestnut  woodland 20 

Advice  to  owners  of  ornamental  chestnut  trees 21 

Advancing  popular  knowledge  of  the  disease 22 

Cooperation  of  the  Department  of  Agriculture 22 

Public  cooperation 23 

The  protection  of  the  Southern  States 23 

Summary 23 


ILLUSTRATIOl^S. 


Page. 
Fig.  1.  Map  showing  the  present  known  distribution  of  the  chestnut  bark 

disease 6 

2.  Large  chestnut  tree  partly  killed  by  the  bark  disease 7 

3.  Diseased  chestnut  bark  showing  pustules  and  form,  of  discharge  of  sum- 

mer spores  in  damp  weather 7 

4.  Dead  chestnut  bark  showing  pustules  of  the  parasitic  fungus  bearing 

winter  spores 8 

467 

3 


Digitized  by  tine  Internet  Archive 

in  2010  with  funding  from 

Boston  Library  Consortium  IVIember  Libraries 


http://www.archive.org/details/controlofchestnu01metc 


B.  P.  I. — 698. 

THE  CONTROL  OF  THE  CHESTNUT  BARK  DISEASE. 


THE  DISEASE. 

HISTORY  AND  DISTRIBUTION. 

The  chestnut  bark  disease  was  first  recognized  as  a  serious  disease 
in  the  vicinity  of  New  Yoric  City  in  1904,  and  the  first  publication 
regarding  it  appeared  in  1906.  There  is  reliable  evidence,  however, 
that  it  was  present  on  Long  Island  at  least  as  early  as  1893,  Its 
origin  is  unknown,  but  there  is  some  evidence  that  it  was  imported 
from  the  Orient  with  the  Japanese  chestnut.  This  view  is  not,  how- 
ever, held  by  all  investigators.  But  whatever  may  have  been  its  time 
or  place  of  origin,  it  is  certain  that  it  has  now  spread  into  at  least 
10  States,  as  is  shown  by  the  accompanying  map  (fig.  1).  In  the 
vicinity  of  New  York  City  and  through  adjacent  counties  it  has 
killed  practically  all  chestnut  trees.  Throughout  a  much  larger 
neighboring  area,  as  shown  in  figure  1,  practically  all  chestnut  trees 
are  infected.  Outside  of  this  area,  throughout  the  country  from  the 
northern  border  of  Massachusetts  and  from  Saratoga  County,  N.  Y., 
to  the  western  border  of  Pennsylvania  and  the  southern  border  of 
Virginia,  scattering  areas  of  infection  are  known  to  occur  and  may 
be  expected  at  any  point. 

So  far  as  is  now  known,  the  bark  disease  is  limited  to  the  true 
chestnuts — that  is,  to  the  members  of  the  genus  Castanea.  The 
American  chestnut,  the  chinquapin,  and  the  cultivated  varieties  of 
the  European  chestnut  are  all  readily  subject  to  the  disease.  Only 
the  Japanese  and  perhaps  other  east  Asian  varieties  appear  to  have 
resistance.  In  spite  of  popular  reports  to  the  contrary,  it  can  be  quite 
positively  stated  that  the  bark  disease  is  not  now  known  to  occur  on 
living  oaks,  horse-chestnuts,  beeches,  hickories,  or  the  golden-leaf 
chinquapin  {Castanopsis  chrysoyhylla)  of  the  Pacific  coast. 

FINANCIAL  LOSSES. 

The  bark  disease  appears  ultimately  to  exterminate  the  chestnut 
trees  in  any  locality  which  it  infests.  A  survey  of  Forest  Park 
(Brooklyn)  showed  "  that  16,695  chestnut  trees  were  killed  in  the 
350  acres  of  woodland  in  this  park  alone.  Of  this  number,  about 
9,000  were  between  8  and  12  inches  in  diameter,  and  the  remaining 
7,000  or  more  were  of  larger  size."  Three  years  ago  the  financial  loss 
from  this  disease  "  in  and  about  New  York  City  "  was  estimated  at 
"  between  five  and  ten  million  dollars." 

The  writers  regard  $25,000,000  as  a  conservative  estimate  of  the 

financial  loss  from  this  disease  up  to  1911.     In  many  localities  the 

greatest  damage  has  been  among  chestnuts  grown  for  ornamental 

purposes,  which  have  a  value  greatly  in  excess  of  their  value  as  lumber. 

467  5 


CONTROL   OP   THE    CHESTNUT   BARK   DISEASE, 


Depression  in  the  value  of  real  estate,  especially  suburban  or  near- 
suburban,  owing  to  the  death  of  the  chestnut  trees,  must  be  taken 
into  account  in  an  estimate  of  this  kind,  as  well  as  the  loss  of  the 
trees  themselves. 

CAUSE  AND  SYMPTOMS. 

The  chestnut  bark  disease  is  caused  by  a  fungus  parasite  known 
under  the  technical  name  of  Diaporthe  parasitica  Murrill.  When 
any  of  the  microscopic  spores  (reproductive  cells)  of  this  fungus  gain 


Fig.  1. — Map  of  the  northeastern  part  of  the  United  States,  showing  the  distribution 
of  the  chestnut  bark  disease.  The  horizontally  lined  part  shows  the  approximate 
area  wherein  the  majority  of  chestnut  trees  are  already  dead  from  the  bark  disease. 
The  part  marked  by  vertical  lines  shows  the  approximate  area  wherein  infection  is 
already  complete.  The  round  dots  show  the  location  of  advance  infections  of  the 
disease.  Many  of  these  have  already  been  eradicated.  The  map  has  been  compiled 
from  both  observations  and  correspondence.  The  writers  are  under  especial  obligations 
to  Dr.  Perley  Spaulding,  Prof.  A.  H.  Graves,  Mr.  I.  C.  Williams,  Mr.  W.  H.  Rankin, 
Mr.  J.  F.  O'Byrne,  Mr.  F.  W.  Besley,  Dr.  Ernest  S.  Reynolds,  and  Mr.  H.  G.  MacMillan, 
for  data  along  this  line.  According  to  Dr.  G.  P.  Clinton  (Connecticut  Agricultural  Ex- 
periment Station,  Report  of  the  Botanist,  1909  and  1910)  there  are  many  more  points 
of  infection  in  Connecticut  than  are  shown  on  this  map. 

entrance  into  any  part  of  the  trunk  or  limbs  of  a  chestnut  tree  they 
give  rise  to  a  spreading  "  sore  "  or  lesion,  which  soon  girdles  the  tree. 
If  the  part  attacked  happens  to  be  the  trunk,  the  whole  tree  in  con- 
sequence is  killed,  perhaps  in  a  single  season.  If  the  smaller  branches 
are  attacked,  only  those  branches  are  killed,  or  only  those  portions  of 
branches  beyond  the  point  of  attack,  and  the  remainder  of  the  tree 
may  survive  for  several  years  (fig.  2). 

467 


CONTROL   OF   THE   CHESTNUT  BARK   DISEASE.  7 

Some  of  the  symptoms  are  quite  prominent.  Limbs  with  smooth 
bark  attacked  by  the  fungus  soon  show  dead,  somewhat  discolored, 
sunken  areas  (occasionally  with  a  raised  margin),  which  continue  to 


Fig.  2. — Large  chestnut  tree  partly  killed  by  the  bark  disease.  Note  the  sprouts 
with  leaves  near  the  top,  the  dwarfed  leaves  on  the  lower  right-hand  limb,  and 
the  healthy  lower  branches  with  leaves. 

enlarge  and  soon  become  covered  more  or  less  thickly  with  yellow, 
orange,  or  reddish- brown  spots  about  the  size  of  a  pinhead.  These 
spots  are  the  pustules  of  the  fruiting  fungus.  In  damp  weather  or 
in  damp  situations,  masses  of  summer  spores  are  extruded  in  the 


Fig. 


3. — Diseased  chestnut  bark  showing  pustules  and  form  of  discharge 
of  summer  spores  in  damp  weather.      (Magnified  3  diameters.) 


form  of  long,  irregularly  twisted  strings  or  "  horns,"  which  are  at 
first  bright  yellow  to  greenish  yellow  or  even  buff,  becoming  darker 
with  age  (fig.  3).  If  the  lesion  is  on  the  trunk  or  a  large  limb  with 
very  thick  bark  there  is  no  obvious  change  in  the  appearance  of  the 

467 


8 


CONTROL    OF    THE    CHESTNUT    BARK   DISEASE. 


bark  itself,  but  the  pustules  show  in  the  cracks  and  the  bark  often 
sounds  hollow  when  tapped.  After  smooth-barked  limbs  or  trunks 
are  girdled  the  fungus  continues  to  grow  extensively  through  the 
bark,  sometimes  covering  the  entire  surface  with  reddish-brown 
pustules  (fig.  4).  These  pustules  produce  mostly  winter  spores 
(ascospores),  although  occasionally  the  long  strings  of  summer  spores 
(fig.  3)  are  also  produced,  even  on  bark  that  has  been  dead  at  least 
a  year. 


^^ 


Fig.  4. — Dead  chestnut  bark  showing  pustules  of  the  parasitic  fungus  bearing  winter 

spores. 

After  a  branch  or  trunk  is  girdled,  the  leaves  change  color  and 
sooner  or  later  wither.  Such  branches  have  a  very  characteristic 
appearance  and  can  hardly  be  mistaken  for  anything  else,  except  in 
certain  localities  where  the  work  of  twig-girdling  insects  may  pro- 
duce a  similar  appearance  in  the  spring.  In  case  the  girdling  by 
the  fungus  is  completed  late  in  the  season,  the  leaves  of  the  follow- 
ing spring  assume  a  yellowish  or  pale  appearance  and  do  not  develop 
to  their  full  size  (fig.  2).  If  the  girdling  is  completed  between  spring 
and  midsummer  the  leaves  may  attain  their  full  size  and  then  turn 

467 


CONTEOL  OF  THE   CHESTKUT  BARK  DISEASE.  9 

a  somewhat  characteristic  reddish-brown  color,  which  can  easily  be 
detected  at  a  long  distance.  Later  this  leaf  coloration  changes  to 
a  more  brownish  tinge  and  the  leaves  are  commonly  persistent  for  a 
considerable  time.  The  chestnut  fruits  (burs)  on  a  spring-girdled 
branch  may  or  may  not  attain  full  size,  according  to  whether  the 
girdling  by  the  disease  was  completed  late  or  early  in  the  spring. 
These  burs  commonly  persist  on  the  tree  during  the  following  win- 
ter, thus  producing  the  only  symptom  which  is  at  all  conspicuous 
during  the  leafless  season.  The  great  damage  which  the  disease  has 
done  in  the  late  summer  thus  becomes  most  evident  at  the  beginning 
of  the  next  season,  and  that  done  in  the  spring  becomes  evident  later 
in  the  same  season,  giving  rise  to  the  false  but  common  idea  that 
the  fungus  does  its  work  at  the  time  of  year  that  the  leaves  change 
color,  when  in  reality  the  harm  was  done  much  earlier. 

Perhaps  the  most  easily  seen  as  well  as  the  longest  persistent 
symptom  of  the  bark  disease  is  the  prompt  development  of  sprouts, 
or  "  suckers,"  on  the  trunk  of  the  tree  (fig.  2)  and  at  its  base,  or 
somewhat  less  frequently  on  the  smaller  branches.  Sprouts  may 
appear  below  every  girdling  lesion  on  a  tree,  and  there  are  usually 
many  such  lesions.  These  sprouts  are  usually  very  luxuriant  and 
quick  growing,  but  rarely  survive  the  second  or  third  year,  as  they 
in  turn  are  killed  by  the  fungus.  The  age  of  the  oldest  living  sprout, 
as  determined  by  the  number  of  its  annual  rings,  is  an  indication  of 
the  minimum  age  of  that  portion  of  the  infection  immediately  above 
it.  Sprouts  are  sometimes  produced  as  a  result  of  other  injuries; 
for  instance,  trees  girdled  by  borers  may  develop  sprouts,  but  these 
are  generally  less  rapid  in  growth  and  are  distributed  with  greater 
uniformity  over  the  trunk.' 

MEANS  OF  SPREAD  AND  ENTRANCE. 

The  disease  is  spread  by  the  spores  of  the  fungus,  of  which  there 
are  two  kinds.  As  both  kinds  of  spores  appear  to  be  sticky,  there 
is  no  evidence  that  they  are  transmitted  by  wind  except  where  they 
may  be  washed  down  into  the  dust  and  so  blown  about  with  the 
dust.  The  spores  are  spread  easily  through  short  distances  by  rain ; 
particularly  they  are  washed  down  from  twig  infections  to  the 
lower  parts  of  the  tree.  There  is  strong  evidence  that  the  spores 
are  spread  extensively  by  birds,  especially  woodpeckers,  and  there 
is  also  excellent  evidence  that  they  are  spread  by  insects  and  by 
various  rodents,  such  as  squirrels.  The  disease  is  carried  bodily  for 
considerable  distances  in  tan  bark  and  unbarked  timber  derived  from 
diseased  trees.  One  of  the  most  prolific  sources  of  general  infection 
has  been  the  transportation  of  diseased  chestnut  nursery  stock  from 
infected  to  uninfected  localities. 
8118°— Bull.  467—11 2 


10  CONTROL  OF   THE   CHESTNUT  BARK  DISEASE. 

When  the  spores  have  once  been  carried  to  a  healthy  tree,  they 
may  develop  in  any  sort  of  hole  in  the  bark  which  is  reasonably  moist. 
These  may  be  wounds  or  mechanical  injuries,  but  by  far  the  most 
common  place  of  infection  is  a  tunnel  made  by  a  borer.  Borers' 
tunnels  are  moist,  even  in  dry  weather,  and  in  them  the  spore  finds 
surroundings  favorable  to  its  development.  In  many  parts  of  the 
country  where  the  disease  is  prevalent  there  is  very  direct  evidence 
that  bark  borers,  and  particularly  the  two-lined  chestnut  borer 
{Agrilus  hilineatus),  are  directly  associated  in  this  way  with  90 
per  cent  or  more  of  all  cases  of  this  disease.  We  are  informed  that 
the  Bureau  of  Entomology  will  issue  a  circular  on  the  insects  as- 
sociated with  the  chestnut  bark  disease. 

The  writers  have  no  definite  evidence,  experimental  or  other- 
wise, to  show  that  a  tree  with  reduced  vitality  is  more  susceptible 
to  infection,  or  that  the  disease  spreads  more  rapidly  in  such  a 
tree,  than  in  a  perfectly  healthy  and  well-nourished  tree  of  either 
seedling  or  coppice  growth,  provided  that  such  reduced  vitality 
does  not  result  in  or  is  not  accompanied  by  bark  injuries  through 
which  spores  can  gain  entrance. 

THE  CONTROL  OF  THE  DISEASE. 

ELIMINATION   AND    QUARANTINE. 
FUNDAMENTAL  OBSERVATIONS  AND   EXPERIMENTS. 

No  method  of  immunizing  individual  trees  against  the  bark  dis- 
ease is  yet  known,  and  no  method  of  treating  or  curing  them  when 
once  attacked  is  certain  in  its  results.  While  this  is  unfortunate 
from  the  standpoint  of  the  owner  of  orchard  trees  and  large  orna- 
mental trees  of  great  individual  value,  no  method  of  dealing  with 
single  trees — surgery,  medication,  spraying,  etc. — however  successful 
in  itself,  would  meet  the  demands  of  the  present  situation.  It  is  not 
practicable  at  present  to  apply  any  individual  method  of  treatment 
to  forest  trees;  the  individual  tree  is  not  worth  it,  and  will  not  be 
for  many  years.  Therefore,  so  far  as  the  chestnut  forests  are  con- 
cerned we  do  not  need  to  regret  particularly  that  no  individual 
treatment  has  yet  been  discovered  that  is  entirely  effective. 

Fortunately,  however,  there  is  a  method  of  dealing  with  the  situa- 
tion which  is  applicable  to  the  country  as  a'  whole  and  which,  so 
far  as  tested,  is  practicable.  Early  in  the  course  of  the  writers' 
investigations  it  became  evident  that  the  disease  advances  but  slowly 
in  a  solid  line,  but  instead  spreads  from  isolated  centers  of  infec- 
tion, often  many  miles  in  advance  of  the  main  line  of  disease. 
That  such  is  the  case  is  evident  from  a  glance  at  figure  1.  It  there- 
fore seemed  probable  that  if  these  advance  infections  could  be  lo- 
cated at  a  reasonably  early  stage,  they  could  be  eliminated  at  rela- 
tively  little  expense,   thus   preventing  further   spread   from   these 

467 


CONTROL  OP   THE   CHESTNUT  BARK  DISEASE.  11 

points  at  least.  Accordingly,  the  country  within  approximately  35 
miles  of  Washington,  D.  C,  was  chosen  in  the  fall  of  1908  as  pre- 
liminary territory  in  which  to  test  this  method  of  control.  This 
section  has  since  been  gone  over  fairly  thoroughly  once  a  year. 
As  will  be  seen  by  figure  1,  14  points  of  infection  were  located,  and 
the  infected  trees  destroyed.  Most  of  this  work  was  done  by  the 
senior  writer.  The  largest  infection  was  a  group  of  nursery  trees 
that  had  been  imported  from  New  Jersey;  the  smallest,  a  single 
lesion  on  a  small  branch  of  a  large  forest  tree.  In  one  case  11  forest 
trees  in  a  group  were  infected,  the  original  infection  having  been 
two  trees,  dating  apparently  from  as  early  as  1907.  Up  to  the 
present  time  (June,  1911)  the  disease  has  not  reappeared  at  any 
point  where  eliminated -and  the  country  within  a  radius  of  approxi- 
mately 35  miles  from  Washington  is  apparently  free  from  the  bark 
disease,  although  new  infections  must  be  looked  for  as  long  as  the 
disease  remains  elsewhere  unchecked.  It  is  therefore  believed  that 
this  method  of  attack  will  prove  equally  practicable  in  other  locali- 
ties, and  if  carried  out  on  a  large  scale  will  result  ultimately  in  the 
control  of  the  bark  disease. 

LEGAL    CONSIDERATIONS. 

In  carrying  such  a  scheme  of  control  into  effect  on  a  large  scale, 
however,  legal  difficulties  are  at  once  encountered.  The  bark  dis- 
ease threatens  the  extinction  of  the  chestnut  throughout  its  range.  As 
it  has  already  been  found  in  at  least  10  States  and  the  District  of 
Columbia,  it  is  essentially  a  national  issue,  but  there  is  no  law 
whereby  the  Federal  Government  can  attempt  to  cope  with  the 
emergency.  Each  State  must  act  on  its  own  initiative  and  control 
the  disease  or  let  it  go  as  its  officers  and  legislative  bodies  see  fit; 
Herein  lies  one  of  the  most  serious  aspects  of  the  matter;  for  if  one 
State  elects  to  undertake  control  of  the  disease  it  will  be  seriously 
handicapped  if  neighboring  States  do  not.  Any  method  of  elimina- 
tion, isolation,  or  quarantine  in  dealing  with  any  disease  of  plants, 
domestic  animals,  or  human  beings  necessitates  general  cooperation. 
It  is  not  practicable  to  try  to  control  the  bark  disease  solely  by  the 
cooperation  of  individual  owners  of  chestnut  woodland,  since  a  sin- 
gle indifferent  or  obstinate  person  can  nullify  the  efforts  of  an  entire 
community.  The  control  of  the  chestnut  bark  disease  must  there- 
fore be  undertaken  by  the  separate  States  under  special  legislation. 
Possibly  in  certain  States  the  crop  and  woodland  pest  laws,  which 
ordinarily  apply  only  to  nursery  stock,  may  be  broad  enough  to 
include  this  disease,  but  in  most  States  the  first  thing  to  be  done 
is  to  obtain  the  necessary  legal  authority  and  an  appropriation  for 
action  along  the  following  lines,  as  has  already  been  done  in  Penn- 
sylvania. 

467 


12  CONTROL,   OF   THE   CHESTNUT   BARK   DISEASE, 

THE    METHOD    IN    DETAIL. 

Locating  advance  infections  ("scouting"). — The  first  thing  to 
be  done  in  each  State  is  to  determine  the  exact  range  of  the  disease 
in  that  State,  and  particuhirly  to  locate  the  advance  points  of  infec- 
tion. This  is  by  far  the  most  difficult  feature  of  the  entire  pro- 
gram, because  the  work  must  be  directed  and  in  large  measure  car- 
ried out  by  experts;  otherwise  diseased  trees  will  be  left,  and  the  re- 
sults can  not  be  depended  upon.  It  is  best  intrusted  to  professional 
plant  pathologists  or  at  least  to  botanists  familiar  with  fungi  and 
the  collecting  of  fungi,  and  even  these  must  have  some  preliminary 
knowledge  of  this  particular  disease.  The  symptoms  of  the  disease 
are  too  obscure  and  the  means  of  locating  it  too  intricate  to  make  it 
possible  for  a  person  without  a  professional  knowledge  of  plant  dis- 
eases to  deal  successfully  with  the  situa,tion,  no  matter  how  well  in- 
formed in  agriculture  or  forestry  or  how  experienced  in  the  care  of 
trees.  It  is  suggested  that  in  most  States  this  part  of  the  work 
would  be  best  handled  by  the  pathologists  of  the  State  agricultural 
experiment  stations. 

For  assistants  the  pathologists  having  this  work  in  charge  should 
choose  the  best  scientific  observers  obtainable,  regardless  of  other  con- 
siderations, but  persons  with  some  knowledge  of  plant  pathology  are 
to  be  preferred.  College  students  trained  in  these  lines  are  usually 
available,  for  the  summer  vacation  at  least,  and  make  in  many 
respects  the  most  desirable  ''  scouts  "  for  this  work.  But  all  "  scouts  '' 
must  be  carefully  and  individually  trained  by  the  expert  in  charge. 

Attention  should  first  be  directed  to  the  advance  spots  of  infection 
already  known  to  exist,  and  when  found  the  diseased  trees  should  be 
destroyed  or  marked  for  destruction.  No  difficulty  will  be  experi- 
enced in  locating  infections  2  years  old  or  more,  but  the  greatest  diffi- 
culty will  be  met  in  locating  infections  of  the  current  year.  Every 
tree  in  the  immediate  vicinity  of  older  infected  trees  must  be  carefully 
gone  over.  Many  dubious  cases  will  be  found,  and  from  such  trees 
samples  of  the  suspected  bark  must  be  taken  and  sent  to  some  labora- 
tory for  expert  judgment.  It  is  absolutely  necessary  to  have  arrange- 
ments with  some  laboratory  whereby  such  work  can  be  done  and  the 
results  promptly  reported. 

After  the  spots  already  known  to  exist  have  been  delimited  and 
the  trees  destroyed  or  marked  for  destruction,  the  search  should  be 
continued.  It  is  best  next  to  clearly  define  the  location  of  the  main 
line  of  advance  of  the  disease,  back  of  which  infection  is  general. 
Working  away  from  this  line  as  a  base,  a  complete  survey  of  the 
remainder  of  the  State  must  be  made,  until  it  is  reasonably  certain 
that  all  spots  have  been  located. 

Scouting  is  best  discontinued  as  soon  as  the  leaves  change  color  in 
the  fall,  since  from  October  to  April,  inclusive,  the  symptoms  are 

467 


CONTROL  OP   THE   CHESTNUT  BARK  DISEASE.  13 

very  obscure.  Practically  no  sign  of  the  disease  is  visible  from  a  dis- 
tance, except  in  those  cases  where  the  burs  persist  on  the  older  trees. 
Even  the  pustules  of  the  fungus  become  weathered,  so  that  even  a 
close  examination  of  a  tree  may  not  yield  visible  results.  But  the 
destruction  of  trees  already  marked  can  continue  through  the  winter. 

Destroying  advance  infections. — Many  of  the  advance  infections 
will  be  found  to  consist  of  single  trees  or  of  less  than  half  a  dozen 
trees.  These  may  perhaps  be  destroyed  by  the  person  who  finds  them, 
especially  if  remote  from  other  infections;  but  the  greater  part  of 
the  work  of  elimination  is  best  handled  by  other  persons  under  sepa- 
rate direction.  Undoubtedly  this  work  can  be  best  directed  in  each 
State  by  the  State  forestry  officials. 

The  work  of  elimination  should  be  done  as  soon  as  possible  after 
the  diseased  trees  are  located,  but  may  be  done  at  whatever  time  of 
year  is  most  convenient,  since  new  infections  will  be  detected  by  the 
scouting  of  the  following  year.  The  marked  trees  should  be  cut 
down.  So  far  as  is  now  known,  the  timber  may  be  safely  utilized  in 
various  ways,  provided  it  is  harked.  The  bark  and  brush  should  be 
piled  over  the  stumps  and,  as  soon  as  practicable,  burned.  If  it  is 
not  practicable  to  have  the  fire  over  the  stumps,  the  stumps  should 
be  barked  to  the  ground;  but  in  any  case  the  bark  and  brush  must 
be  burned. 

It  will  be  readily  seen  that  the  task  of  locating  the  disease,  and  the 
subsequent  one  of  eliminating  it,  call  for  very  different  talents.  The 
"  scouting  "  calls  for  carefully  trained  and  absolutely  accurate  scien- 
tific observers  working  under  the  most  highly  specialized  direction 
that  can  be  obtained.  The  work  of  elimination  calls  not  for  scien- 
tific knowledge,  but  for  executive  ability,  tact  in  dealing  with" 
owners  and  in  otherwise  administering  the  law,  and  a  Imowledge  of 
forestry  and  of  lumbering,  market,  and  transportation  conditions. 
In  a  word,  the  first  is  a  task  for  pathologists,  the  second  for  foresters. 
Another  advantage  of  thus  dividing  the  work  is  that  a  certain  rivalry 
will  usually  develop,  resulting  in  more  thorough  work  on  both  sides. 
It  is,  moreover,  of  the  utmost  importance  to  have  as  many  different 
forces  and  interests  as  possible  in  any  given  State  working  toward 
the  common  end  of  controlling  this  disease. 

Establishing  the  "  immune  zone." — After  all  advance  spots  of 
infection  are  eliminated,  attention  must  be  turned  to  the  main  line 
of  advance — the  edge  of  the  area  of  general  infection.  Here  the 
problem  will  present  local  differences.  It  may  prove  necessary  in 
some  States  to  destroy  all  chestnut  trees,  diseased  or  healthy,  in  a 
belt  10  to  20  miles  wide,  or  possibly  less.  Advantage  must  be  taken 
of  natural  barriers  to  infection,  such  as  unforested  areas  or  wooded 
areas  without  chestnuts.  In  this  way  an  "  immune  zone "  will  be 
established,  across  which  the  disease  can  not  easily  be  transmitted  by 

467 


14  CONTROL   OF   THE   CHESTNUT   BARK   DISEASE. 

merely  local  agents.  Back  of  this  line  the  chestnut  trees  may  be 
abandoned  to  the  disease.  Every  effort  should  be  made,  however,  to 
have  them  cut  down  and  the  timber  utilized  as  soon  as  possible, 
since  they  remain  sources  of  distant  infection  as  long  as  any  spore- 
laden  bark  or  diseased  sprouts  remain  on  them. 

Quarantine. — Whether  any  restrictions  are  placed  upon  the  move- 
ment of  chestnut  products  from  the  area  of  complete  infection  to  the 
protected  territory  will  depend  largely  on  local  conditions  and  must 
be  left  to  the  judgment  of  State  authorities.  Barked  timber  can 
probably  be  moved  with  comparative  safety.  It  will  always  be  de- 
sirable to  limit  the  movement  of  unbarked  chestnut  timber  and  fire- 
wood and  of  chestnut  tan  bark.  An  inspection  of  local  conditions 
will  readily  determine  whether  the  danger  from  these  sources  is 
sufficiently  great  to  warrant  the  business  inconvenience  which  would 
be  caused  by  the  quarantine  of  any  or  all  chestnut  products. 

Program  for  the  second  year, — The  work  for  the  second  year  will 

consist  mostly  of  reinspection  of  the  advance  spots  where  the  bark 

disease  has  been  eradicated  the  previous  year  and  of  general  scouting 

to  locate  new  spots.    If  the  work  of  the  first  year  has  been  thoroughly 

done  and  there  has  been  time  to  complete  the  elimination  of  all  spots 

located,  only  scattering  infections  may  be  expected.    From  this  time 

on  the  persons  in  charge  of  scouting  will  have  the  bulk  of  work  and 

responsibility. 

THE   EXAMPLE    OF   PENNSYLVANIA. 

Pennsylvania  enjoys  the  distinction  of  being  the  first  and  so  far  the 
only  State  to  undertake  in  any  way  the  control  of  the  chestnut  bark 
disease.  In  the  summer  of  1910  the  Main  Line  Citizens'  Associa- 
tion— an  organization  of  citizens  residing  along  the  main  line  of  the 
Pennsylvania  Railroad  near  Philadelphia — appointed  a  committee  of 
seven,  under  the  chairmanship  of  Mr.  Harold  Peirce,  to  determine  the 
status  of  the  disease  in  that  locality  and  to  see  what  could  be  done 
toward  controlling  it.  An  extensive  local  survey  of  the  disease  was 
made  under  the  direction  of  Mr.  I.  C.  Williams,  deputy  State  forest 
commissioner.  The  committee  soon  became  convinced  that  the  prob- 
lem was  of  State  and  even  national  importance,  and  could  only  be 
solved  by  legislation  and  by  the  broadest  cooperation.  Accordingly 
they  devoted  their  energies  to  securing  the  passage  by  the  Pennsylva- 
nia Legislature  of  the  following  bill,  which  has  now  become  a  law. 
This  law  is  almost  unique  in  conservational  legislation,  and  on  ac- 
count of  its  important  bearing  as  precedent  for  similar  laws  in  other 
States  it  is  here  reproduced  in  full. 

AN  ACT  To  provide  efficient  and  practical  means  for  the  prevention,  control,  and  eradica- 
tion of  a  disease  aftecting  chestnut  trees,  commonly  called  the  chestnut-tree  blight ;  pro- 
viding for  the  destruction  of  trees  so  affected  ;  creating  a  commission  to  carry  out  the 
purpose  of  this  act ;  fixing  penalties  for  violation  of  the  provisions  hereof ;  and  making 
an  appropriation  therefor. 
Section  1.  Be  it  enacted  dy  the  Senate  and  House  of  Representatives  of  the 

Commonwealth  of  Pennsylvania  in  General-  AssemUy  met;  and  it  is  herehy 
467 


CONTROL  OF  THE   CHESTNUT  BAUK  DISEASE.  15 

enacted  hy  the  authoriti/  of  the  same:  That  a  commission  to  consist  of  five 
members,  to  be  appointed  by  the  Governor  for  a  period  of  three  years  from  the 
date  of  the  approval  of  this  act,  and  to  be  called  "  The  Commission  for  the  In- 
vestigation and  Control  of  the  Chestnut-Tree  Blight  Disease  in  Pennsylvania," 
is  hereby  created,  with  power  to  ascertain,  determine  upon,  and  adopt  the 
most  efficient  and  practical  means  for  the  prevention,  control,  and  eradication 
of  a  disease  of  the  chestnut  tree  commonly  known  as  the  chestnut-tree  blight 
disease ;  and  for  this  puii^ose,  in  collaboration  with  the  department  of  forestry, 
or  otherwise,  to  conduct  scientific  investigations  into  the  nature  and  causes  of 
such  disease  and  the  means  of  preventing  its  introducton,  continuance,  and 
spread;  to  establish,  regulate,  maintain,  and  enforce  quarantine  against  the 
introduction  and  spread  of  such  disease ;  and,  from  time  to  time,  to  adopt  and 
prescribe  such  regulations  and  methods  of  procedure  as  to  it  may  seem  neces- 
sary and  proper  for  carrying  into  effect  the  purpose  of  this  act,  and  exercising 
the  powers  and  authority  hereby  conferred:  Provided,  That  in  the  work  of 
collaboration  by  the  commission  with  the  Department  of  Forestry  said  depart- 
ment may  employ  such  means,  and  make  detail  of  such  men,  and  do  such  other 
things,  as  may  seem  to  be  necessary  or  expedient  to  accomplish  the  purpose  of 
this  act. 

Sec.  2.  Any  member  of  the  commission,  or  any  of  its  duly  authorized  agents 
or  employees,  shall  have  the  right,  at  any  time,  to  enter  upon  any  premises,  wild 
lands,  farms,  fields,  private  grounds,  and  inclosures  for  the  purpose  of  examin- 
ing into  the  condition  of  any  chestnut  tree  or  trees  thereon,  and  determining 
whether  or  not  such  trees,  or  any  of  them,  have  been  attacked  or  infected  by 
the  chestnut-tree  blight ;  and  whenever  this  disease  is  found  to  exist,  such 
commissioners,  their  duly  authorized  agents  and  employees,  shall,  in  all  prac- 
ticable ways,  cooperate  with  the  owners  of  such  trees  in  and  for  the  removal, 
cure,  control,  and  eradication  of  such  disease,  and  the  prevention  of  its  spread 
to  other  chestnut  trees  upon  adjoining  and  other  properties;  shall  specifically 
advise  and  direct  such  owner  how  he  shall  proceed  for  the  accomplishment  of 
these  ends ;  and  shall  leave  with  such  owner,  his  agent,  tenant,  or  other  repre- 
sentative having  charge  of  such  trees,  a  notice,  in  writing,  containing  a  descrip- 
tion or  plan  specifically  designating  the  trees  so  found  to  be  diseased,  and 
full  and  specific  instructions  for  the  treatment  of  such  trees,  or  for  the  removal 
and  destruction  of  designated  parts  thereof  or  of  an  entire  tree  or  trees,  as 
the  case  may  require. 

Sec.  3.  If  any  owner  of  such  trees,  so  found  to  be  diseased  by  the  said  com- 
mission, its  duly  authorized  agents  or  employees,  shall  neglect  or  refuse  to 
cooperate  in  applying  the  necessary  remedies  for  the  removal,  cure,  control, 
and  eradication  of  such  disease,  and  the  prevention  of  its  spread  to  other 
chestnut  trees  upon  adjoining  and  other  properties;  or  shall  neglect  or  refuse 
to  comply  with  the  requirements  of  the  notice  aforesaid,  prescribing  the  treat- 
ment which  shall  be  applied  to  such  trees,  so  found  to  be  diseased,  within 
twenty  days  from  the  time  such  notice  shall  have  been  served,  the  said  com- 
mission may  at  once  proceed,  through  its  duly  authorized  agents  and  employees, 
to  do  whatever  may  be  found  by  it  to  be  necessary  and  proper  to  accomplish 
the  cure,  control,  or  eradication  of  such  disease  and  the  prevention  of  its 
spread  to  other  chestnut  trees ;  and  for  this  purpose,  whenever  it  may  be  found 
necessary  may  remove,  cut  down,  and  destroy,  or  cause  to  be  removed,  cut  down, 
or  destroyed,  any  trees  or  parts  of  trees  so  found  to  be  infected  with  such 
disease;  and  shall  immediately  thereafter  duly  certify  to  the  owner  of  such 
trees,  so  treated  or  destroyed,  or  to  his  tenant,  agent,  or  other  representative 
in  charge  of  such  trees,  the  amount  of  the  cost  or  expenses  actually  incurred 
by  the  commission  in  the  treatment,  removal,  or  destruction  of  such  trees ;  and 
467 


16  CONTROL   O^   THE    CHESTNUT   BARK   DISEASE. 

if  the  amount  of  such  expense,  so  certified,  shall  not  be  paid  by  such  owner  of 
said  trees,  so  treated,  removed,  or  destroyed  within  sixty  days  after  it  shall 
have  been  so  certified,  the  same  may  be  recovered  by  the  said  commission, 
from  such  owner,  by  an  action  in  the  name  of  the  Commonwealth,  in  the  same 
manner  as  debts  of  like  amount  are  now  recoverable,  and  when  recovered  may 
be  used  by  said  commission  in  carrying  out  the  purposes  of  this  act. 

Provided,  Iwivevcr,  That  any  owner  or  owners  of  trees,  his  or  their  tenants, 
agents,  or  representatives,  who  may  be  dissatisfied  with  any  decision,  order,  or 
notice  of  any  member  of  the  commission,  or  any  of  its  agents  or  employees, 
directing  or  prescribing  the  treatment,  removal,  or  destruction  of  trees  belonging 
to  or  controlled  by  them,  shall  have  the  right  within  ten  days  from  the  time 
of  the  service  upon  them  of  such  order  or  notice  to  appeal  therefrom,  in 
writing,  to  the  commission,  which  shall  thereupon,  withoiit  avoidable  delay, 
direct  a  re-examination  of  the  premises  or  trees  in  question,  by  competent 
experts,  who  shall  make  report  of  their  findings  to  the  commision ;  which  shall 
then  fix  a  time  and  a  place  for  a  hearing  before  it,  upon  such  appeal,  and 
notify  the  person  making  appeal  thereof.  All  further  proceedings  under 
such  order  or  notice  shall  be  suspended  until  the  decision  of  the  commission 
shall  have  been  formally  rendered. 

Sec.  4.  Whenever,  in  the  judgment  of  the  commission,  it  may  be  necessary 
to  destroy  chestnut  trees  not  affected  by  the  chestnut-tree  blight,  for  the  pur- 
pose of  establishing  a  quarantine  to  prevent  and  control  the  spread  of  the 
disease,  the  owner  of  such  trees  shall  be  reimbursed  for  the  loss  of  all  the 
good  and  unaffected  trees  so  destroyed;  the  amount  to  be  paid  therefor  to 
be  not  greater  than  the  stumpage  prices  of  such  trees,  prevailing  at  the  time 
in  the  locality  where  such  trees  grew ;  such  value  to  be  determined  by  the  com- 
mission, by  such  method  or  procedure  as  it  may  adopt,  and  payment  therefor 
to  be  made  from  the  fund  hereinafter  specifically  appropriated  for  the  use  ol 
the  said  commission  in  performing  the  duties  required  by  this  act.  Should  any 
owner  of  trees  be  dissatisfied  with  the  amount  awarded  to  pay  for  the  destruc- 
tion of  such  good  and  unaffected  trees,  said  owner  shall  have  all  the  remedies 
now  existing,  or  which  may  hereafter  be  provided  by  law,  for  the  protection  of 
his  interests. 

Sec.  5.  Any  person  who  shall  wilfully  violate  any  of  the  provisions  of  this 
act,  or  any  of  the  regulations  of  the  commission  intended  to  assist  in  carrying 
this  act  into  effect,  or  shall  wilfully  resist  or  Interfere  with  any  agent  or 
employee  of  the  said  commission  in  the  performance  of  his  duties  in  accordance 
with  the  regulations  and  orders  of  the  commission,  under  the  provisions  hereof, 
shall  be  deemed  guilty  of  misdemeanor,  and  shall  upon  conviction  thereof  be 
punished  by  a  fine  not  exceeding  one  hundred  dollars,  or  by  imprisonment  not 
exceeding  one  month,  either  or  both,  at  the  discretion  of  the  court.  The  word 
"  person,"  as  used  in  this  act,  shall  include  not  only  individuals  or  natural 
persons,  but  as  well  artificial  persons,  existing  only'  in  contemplation  of  law, 
and  shall  be  construed  to  mean  partnerships,  limited  partnerships,  joint-stock 
companies,  and  corporations,  and  the  officers,  agents,  and  employees  of  the  same. 

Sec.  6.  The  members  of  the  commission  shall  serve  without  pay,  but  shall 
be  reimbursed  for  all  actual  expense  incurred  by  them  in  exercising  the  powers 
conferred  upon  them  and  performing  the  duties  required  by  this  act.  The 
employees  of  the  commission  shall  receive  such  compensation  for  their  services 
as  the  commission  shall  determine  will  fairly  compensate  them  for  the  work 
to  be  done.  The  commission  shall  be  furnished  with  suitable  rooms  in  the 
Capitol  building  at  Harrisburg,  or  elsewhere,  by  the  Superintendent  of  Public 
Grounds  and  Buildings.  The  sum  of  twenty-five  thousand  dollars  Is  hereby 
specifically  appropriated,  to  be  immediately  available  upon  the  approval  of  this 
467 


CONTROL  OF   THE   CHESTNUT  BARK  DISEASE.  17 

act,  for  the  payment  of  such  expense  as  may  be  incurred  by  the  commission,  for 
such  scientific  research  and  for  office  expenses,  as  in  their  judgment  may  be 
necessary  to  comply  with  tl\e  provisions  hereof,  said  appropriation  to  be  avail- 
able until  the  first  day  of  June,  Anno  Domini,  one  thousand  nine  hundred  and 
thirteen ;  and  the  further  sum  of  two  hundred  and  fifty  thousand  dollars,  or  so 
much  thereof  as  shall  be  necessary,  is  hereby  specifically  appropriated,  to  be 
available  only  upon  the  approval  of  the  Governor,  for  the  performance  of  all 
other  duties  herein  required  to  be  done;  as,  for  quarantine,  removal  of  diseased 
trees  or  other  trees,  conducting  outside  investigations  and  operations,  and 
every  other  means  of  eradication  and  control,  as  to  it  may  seem  necessary  in 
complying  with  the  provisions  hereof. 

Sec.  7.  All  acts  or  parts  of  acts  inconsistent  herewith  are  hereby  repealed. 

The  commission  authorized  by  the  bill  has  been  appointed  by  the 
governor  of  Pennsylvania  and  consists  of  the  following  persons: 
Mr.  Winthrop  Sargent,  chairman;  Mr.  Harold  Peirce,  secretary; 
Messrs.  Samuel  T.  Bocline,  George  F.  Craig,  and  Theodore  N.  Ely. 
Persons  desiring  information  regarding  the  work  on  this  disease  in 
Pennsylvania  should  address  the  executive  officer  of  the  commission, 
Mr.  Samuel  B.  Detweiler,  1112  Morris  Building,  Philadelphia,  Pa. 

INSPECTION  OF  DISEASED  NURSERY  STOCK. 

As  has  been  indicated,  diseased  chestnut  nursery  stock  has  in  the 
past  been  a  most  important  factor  in  the  spread  of  the  bark  disease. 
On  account  of  a  well-grounded  fear  of  this  disease  much  less  nursery 
stock  is  being  moved  now  than  formerly,  but  there  is  still  enough  to 
constitute  a'  serious  source  of  danger.  It  is  therefore  obvious  that 
every  State  in  which  the  chestnut  grows,  either  naturally  or  under 
cultivation,  should  as  speedily  as  possible  pass  a  law  putting  the 
chestnut  bark  disease  on  the  same  footing  as  other  pernicious  diseases 
and  insect  pests,  such  as  peach  yellows  and  the  San  Jose  scale,  against 
which  quarantine  measures  are  taken.  Many  inspectors  already  have 
legal  power  to  quarantine  against  the  bark  disease  on  chestnut  nurs- 
ery stock,  and  they  should  now  take  special  care  that  no  shipment, 
however  small,  escapes  their  rigid  inspection. 

The  most  serious  practical  difficulty  in  inspecting  nursery  stock  for 
this  as  for  other  fungous  diseases  lies  in  the  fact  that  practically  all 
State  inspectors  are  necessarily  entomologists,  and  are  not  trained  in 
recognizing  the  more  obscure  symptoms  of  fungous  diseases.  Nursery 
trees  affected  by  the  bark  disease  rarely  show  it  prominently  at  the 
time  when  shipped;  the  threads  of  summer  spores  or  the  yellow  or 
orange  pustules  are  rarely  present,  and  usually  all  the  inspector  can 
find  is  a  small,  slightly  depressed,  dark-colored  area  of  dead  bark, 
usually  near  the  ground,  which  is  easily  overlooked  or  mistaken  for 
some  insignificant  injury.  Upon  cutting  into  such  a  spot,  the  inner 
bark  shows  a  most  characteristic  disorganized  "  punky  "  appearance, 
quite  different  from  that  of  any  other  bark  injury;  but  it  is  im- 
possible to  adequately  describe  this  appearance  without  recourse  to 
colored  illustrations.     Occasionally  a  yellowish-brown  band,  either 

467 


18  CONTROL   OP   THE    CHESTNUT   BARK  DISEASE. 

girdling  or  partly  girdling  the  young  tree,  may  be  seen ;  this  is  very 
characteristic,  but  is  so  prominent  a  symptom  that  it  may  be  noticed 
at  the  nursery,  and  presumably  trees  so  affected  will  not  be  shipped. 
If  infected  trees  are  set  out  they  develop  the  disease  with  its  char- 
acteristic symptoms  the  following  spring.  But  on  account  of  their 
small  size  such  trees  are  girdled  and  die  before  the  end  of  the  sum- 
mer, often  in  two  or  three  weeks.  Meanwhile  they  are  spreading 
the  disease  to  neighboring  orchard  and  forest  trees.  Orchardists 
and  nurserymen  purchasing  chestnut  trees  are  therefore  warned  to 
watch  them  closely  during  the  first  season,  no  matter  how  rigidly 
they  may  have  been  inspected. 

INDIVIDUAL   TREATMENT   OF   DISEASED   TREES. 

Where  valuable  ornamental,  shade,  or  orchard  chestnut  trees  be- 
come infected  in  one  or  more  spots,  the  life  and  usefulness  of  such 
trees  can  be  prolonged  for  several  or  for  many  years,  depending 
largely  upon  the  thoroughness  with  which  the  recommendations 
herein  given  for  cutting  out  the  diseased  areas  (lesions)  are  carried 
out.  These  recommendations  are  based  upon  the  results  of  extensive 
experiments  with  hundreds  of  lesions  during  the  past  four  years. 
These  experiments  were  performed  for  the  most  part  by  the  junior 
writer. 

The  essentials  for  the  work  are  a  gouge,  a  mallet,  a  pruning  knife, 
a  pot  of  coal  tar,  and  a  paint  brush.  In  the  case  of  a  tall  tree  a 
ladder  or  rope,  or  both,  may  be  necessary,  but  under  no  circumstances 
should  tree  climbers  be  used,  as  they  cause  wounds  which  are  very 
favorable  places  for  infection.  Sometimes  an  ax,  a  saw,  and  a  long- 
handled  tree  pruner  are  convenient  auxiliary  instruments,  though 
practically  all  the  cutting  recommended  can  be  done  with  a  gouge 
with  a  cutting  edge  of  1  or  1^  inches.  All  cutting  instruments 
should  be  kept  very  sharp,  so  that  a  clean  and  smooth  cut  may  be 
made  at  all  times. 

By  cutting  with  the  gouge  into  a  diseased  area  a  characteristically 
discolored  and  mottled  middle  and  inner  bark  is  revealed.  All  of 
this  diseased  bark  should  be  carefully  cut  out  for  tit  least  an  inch 
beyond  the  discolored  area  if  the  size  of  the  branch  will  allow  it. 
This  bark  should  be  collected  in  a  bag  or  basket  and  burned.  If  the 
cutting  is  likely  to  result  in  the  removal  of  the  bark  for  much  more 
than  half  the  circumference  of  the  branch  or  trunk,  it  will  probably 
be  better  to  cut  off'  the  entire  limb  or  to  cut  down  the  tree,  as  the 
case  may  be,  unless  there  is  some  special  reason  for  attempting  to 
save  the  limb  or  tree.  The  fungus  usually,  though  not  always,  de- 
velops most  vigorously  in  the  inner  bark  next  to  the  wood.  When 
this  is  the  case,  not  only  all  the  diseased  bark  and  an  inch  of  healthy 
bark  around  it  must  be  removed,  but  at  least  two  or  three  annual 
layers  of  wood  beneath  the  diseased  bark  must  also  be  gouged  out. 
Special  care  should  be  taken  to  avoid  loosening  the  healthy  bark  at 

467 


CONTROL   OF   THE   CHESTNUT  BARK  DISEASE.  19 

the  edges  of  the  cut-out  areas.  Except  in  the  early  spring  this  is 
not  diificult  after  a  little  experience  in  manipulating  the  gouge  and 
mallet,  provided  the  gouge  is  kept  sharp. 

Small  branches  which  have  become  infected  should  be  cut  off,  the 
cut  being  made  well  back  of  the  disease — at  least  2  or  3  inches,  if 
possible. 

All  cut-out  areas  and  all  the  cut  ends  of  stubs  should  be  carefully 
and  completely  painted  with  coal  tar.  A  good  grade  of  paint  has 
been  recommended  by  some  authorities  as  superior  to  tar,  but  it  is 
more  expensive.  If  the  tar  is  very  thick,  the  addition  of  a  little  creo- 
sote will  improve  it  for  antiseptic  purposes  as  well  as  for  ease  in 
applying.  If  the  first  coat  is  thin,  a  second  one  of  fairly  thick  tar 
should  be  applied  within  a  few  weeks  or  months.  Other  coats  should 
be  applied  later  whenever  it  becomes  necessary. 

The  entire  tree  should  be  carefully  examined  for  diseased  spots  and 
ever}^  one  thoroughly  cut  out  and  treated  in  the  way  already  de- 
scribed. In  case  of  suspicious  looking  spots  a  portion  of  the  outer 
bark  can  be  cut  out  with  the  sharp  gouge  as  a  test.  If  this  cut  shows 
the  characteristically  discolored  bark  the  spot  can  be  considered  as 
diseased  and  cut  out  accordingly;  if  the  cut  shows  healthy  bark,  it 
need  merely  be  treated  with  tar  or  paint,  as  other  cuts  are  treated. 
In  examining  a  tree  for  diseased  spots  it  is  always  best  to  begin  at 
the  base  of  the  trunk  and  work  up,  for  if  the  trunk  is  girdled  at  the 
base  it  is  useless  to  work  anywhere  on  the  tree. 

"When  the  spores  of  the  fungus  are  present,  especially  in  the  form 
of  threads,  or  "horns,"  they  are  readily  washed  down  the  branches 
and  trunk  by  every  rain,  and  are  thus  carried  down  to  or  toward 
the  base  of  the  tree.  As  a  result  the  base  of  a  tree,  the  crotches,  and 
other  places  which  afford  easy  lodgment  for  the  spores  are  particu- 
larly subject  to  infection. 

Although  spraying  with  any  of  the  standard  fungicides  appears 
to  have  no  effect  whatever  in  stopping  the  progress  of  the  disease 
after  it  has  once  started  in  the  inner  or  middle  bark,  there  is  little 
doubt  that  it  is  of  use  in  preventing  infection  from  spores  washed 
down  by  rain  from  the  upper  part  of  a  tree  or  from  spores  which 
have  been  transported  from  other  trees.  For  this  reason  the  spray- 
ing, after  each  rain,  of  the  parts  of  a  tree  below  a  spore-bearing 
lesion  is  recommended,  but  only  on  an  experimental  basis.  If  no 
spore-bearing  lesions  occur  on  the  tree,  there  is  less  apparent  reason 
for  spraying.  The  scattering  of  slaked  lime  about  the  base  of  a  tree 
and  the  whitewashing  of  the  trunk  and  larger  limbs  have  shown 
apparently  beneficial  results  in  preventing  infections  and  perhaps 
also  depredations  of  borers. 

A  tree  which  is  being  treated  for  individual  infections  must  be 
carefully  watched  and  the  diseased  spots  promptly  cut  out  as  they 
appear.  For  this  purpose  each  tree  should  be  examined  very  care- 
fully two  or  three  times  at  least  during  the  growing  season. 

467 


20  CONTROL   OF   THE   CHESTNUT   BARK   DISEASE. 

The  Department  of  Agriculture  asks  the  cooperation  of  all  persons 
who  have  experimented  with  the  disease  in  any  way,  and  in  return 
is  ready  to  give  specific  advice,  based  upon  extensive  experience  with 
the  disease,  as  to  the  best  methods  of  attempting  its  control  or  as  to 
what  are  likely  to  be  the  most  profitable  systematic  observations  or 
experiments. 

ADVICE  TO  CHESTNUT  ORCHARDISTS. 

In  view  of  the  uncertain  future  of  the  chestnut  tree,  the  Depart- 
ment of  Agriculture  advises  against  planting  chestnuts  anywhere  east 
of  Ohio,  at  least  until  it  is  settled  what  efforts  will  be  made  by  the 
individual  States  to  control  the  bark  disease.  The  only  exception  is 
that  Japanese  chestnuts  may  be  grown  if  raised  from  imported  seeds 
and  not  grafted  on  American  stocks.  If  the  seed  is  raised  in  America, 
the  trees  are  more  than  likely  to  be  hybrids  with  the  American  chest- 
nut and  to  vary  greatly  in  resistance  to  the  bark  disease.  If  grafted 
on  American  stocks,  the  stocks  readily  succumb  to  the  disease,  and 
so  the  whole  tree  is  killed,  no  matter  how  resistant  the  scion  may  be. 
However,  the  nut  of  the  true  Japanese  chestnut  is  of  poor  quality  at 
best,  and  it  is  an  open  question  whether  it  can  ever  be  made  a 
commercial  success. 

West  of  the  natural  range  of  the  American  chestnut,  however,  the 
situation  is  quite  different.  Obviously  the  western  chestnut  orchard- 
ist  has  before  him  a  great  opportunity.  No  matter  how  successful 
efforts  to  limit  the  bark  disease  in  the  East  may  be,  the  nut  crop  will 
be  reduced  for  some  years,  and  the  business  of  growing  fine  orchard 
chestnuts  in  the  East  will  be  depressed  for  the  same  length  of  time. 
There  is  no  apparent  reason  why,  with  rigid  inspection,  both  of  any 
purchased  stock  and  of  the  orchards  themselves,  all  chestnut  orchards 
and  nurseries  from  Ohio  to  the  Pacific  coast  can  not  be  kept  perma- 
nently free  from  the  bark  disease;  therefore  all  persons  interested  in 
growing  the  chestnut  in  the  West  as  an  orchard  tree  are  earnestly 
advised  not  to  secure  any  chestnut  nursery  stock  from  eastern  nur- 
series ;  to  be  sure  that  stock  from  any  source  is  rigidly  inspected ;  to 
watch  with  the  utmost  care  their  own  nurseries  and  orchards ;  and  to 
destroy  immediately  by  fire  any  trees  that  may  be  found  diseased. 

There  is  presumptive  evidence  that  the  bark  disease  was  introduced 
into  America  on  the  Japanese  chestnut,,  but  until  this  point  is  defi- 
nitely settled  orchardists  west' of  Ohio  are  advised  not  to  import  nur- 
sery stock  of  this  variety.  Seed  can  probably  be  imported  with  a 
reasonable  degree  of  safety,  however. 

ADVICE  TO   OWNERS  OF  CHESTNUT  WOODLAND. 

Owners  of  chestnut  woodland  anywhere  within  the  area  of  com- 
plete infection  are  earnestly  advised  to  convert  their  trees  into  lumber 
as  quickly  as  possible.  The  trees  that  are  not  already  killed  will  soon 
die  in  any  case  and  the  timber  will  quickly  deteriorate  in  quality.    Such 

467 


CONTROL  OF   THE   CHESTNUT  BARK  DISEASE.  21 

trees  are  a  continual  source  of  further  infection,  and,  moreover,  large 
areas  of  dead  chestnut  trees,  by  harboring  bark  and  wood  inhabit- 
ing insects,  are  likely  to  start  some  insect  epidemic.  Indeed,  with  the 
quantity  of  dead  chestnut  timber  now  standing  it  will  be  remarkable 
if  some  serious  infestation  of  insects  extending  to  sound  trees  does 
not  follow. 

Owners  of  chestnut  woodland  outside  the  area  of  general  infection 
are  counseled  to  watch  for  the  first  appearance  of  the  disease,  and 
when  it  appears  to  cut  down  immediately  all  affected  trees,  bark 
them,  and  burn  the  bark  and  brush,  over  the  stump  if  practicable. 
Such  procedure  will  distinctly  retard  the  spread  of  the  disease  in 
that  particular  woodland,  even  if  no  concerted  efforts  at  elimination 
are  made  by  neighboring  owners.  It  is  to  be  expected,  however,  that 
in  all  cases  of  this  kind  the  owner  will  have  the  cooperation  of  the 
State  authorities  in  a  general  quarantine  movement. 

It  is  almost  needless  to  add  that  until  we  know  what  action  is  to 
be  taken  in  all  the  chestnut-growing  States  and  what  the  results  are 
likely  to  be,  chestnut  woodland  is  a  poor  investment.  Furthermore, 
in  forest  management,  as  in  improvement  cuttings,  etc.,  there  should 
be  discrimination  against  the  chestnut. 

ADVICE    TO    OWNERS    OF    ORNAMENTAL    CHESTNUT    TREES. 

Until  the  future  of  the  chestnut  tree  is  better  known,  or  at  least 
until  we  know  what  legalized  action  is  going  to  be  taken  in  the 
States  concerned,  the  owners  of  chestnut-timbered  land  available  for 
building  should  pursue  a  very  conservative  policy.  Houses  should 
not  be  located  with  sole  reference  to  chestnut  groves  or  to  isolated 
ornamental  chestnut  trees.  Houses  so  located  should  be  discrimi- 
nated against  in  purchasing  homes  in  so  far  as  the  death  of  the 
chestnut  trees  would  injure  the  appearance  of  the  place. 

When  ornamental  trees  become  diseased  they  had  better  be  cut 
down  at  once  and,  if  practicable,  large  trees  of  other  species  moved 
in  to  take  their  places.  In  expert  hands  the  moving  of  large  trees  is 
a  perfectly  practicable  and  successful  procedure  and,  although  more 
expensive,  is  much  more  satisfactory  than  waiting  for  nursery  trees 
to  grow.^ 

All  owners  of  diseased  ornamental  chestnut  trees  are  specifically 
warned  against  "  fake  "  tree  doctors.  Large  sums  of  money  have 
been  paid  out  in  many  cases  for  treatment  that  has  been  worse  than 
useless.  Reliable  tree  specialists  will  have  nothing  to  do  with  trees 
affected  with  the  chestnut  bark  disease,  or,  if  they  do  anything,  do  it 
with  the  distinct  understanding  in  advance  that  it  is  entirely  at  the 

1  In  case  such  action  is  not  immediately  desirable  or  possible,  a  very  good,  though  tem- 
porary, scenic  effect  can  be  obtained  by  lopping  off  the  ends  of  the  larger  branches  of  the 
dead  and  dying  chestnut  trees,  removing  the  bark,  and  planting  some  rapid-growing  vine  at 
their  foot,  which  soon  covers  them.  One  of  the  best  for  this  purpose  is  the  Japanese  kudzu 
vine  (Pueraria  thunhergiana  (S.  and  Z.)  (Benth.),  on  account  of  its  extraordinarily  rapid 
growth.  Such  vine-covered  stumps  must  be  carefully  watched,  however,  for  in  a  very  few 
years  they  decay  and  are  liable  to  be  blown  over. 
467 


22  CONTROL   OP   THE   CHESTNUT   BARK  DISEASE. 

owner's  risk.    Of  course,  if  an  owner  desires  to  employ  tree  surgeons 
to  experiment,  that  is  another  matter. 

ADVANCING  POPULAR  KNOWLEDGE  OF  THE  DISEASE. 

In  the  localities  where  infection  is  general  or  complete  (fig.  1) 
everyone  knows  what  the  chestnut  bark  disease  is  and  what  its  symp- 
toms are  and  everyone  appreciates  its  seriousness ;  but  in  these  local- 
ities it  is  too  late  even  to  attempt  its  control.  On  the  other  hand,  in 
Delaware,  Virginia,  West  Virginia,  western  and  southern  Mary- 
land, western  Pennsylvania,  central  and  northern  New  York,  Massa- 
chusetts, and  Rhode  Island  very  few  people  know  the  symptoms  of 
the  disease.  On  this  account  no  one  notices  it  until  it  is  thoroughly 
established,  and  by  the  time  public  sentiment  is  sufficiently  aroused 
to  authorize  the  necessary  legislation  and  bring  about  united  action 
for  public  protection  it  is  too  late  for  such  action  to  be  of  service. 
Obviously,  then,  every  effort  should  be  made  by  all  State  and  other 
officials  having  such  matters  in  charge  to  acquaint  every  citizen  with 
the  prominent  symptoms  of  the  bark  disease  and  to  familiarize  him 
with  the  fact  that  unless  prompt  and  united  action  is  taken  there 
is  every  indication  that  the  chestnut  tree  in  the  States  above  men- 
tioned will  become  practically  extinct  within  10  years. 

COOPERATION  OF  THE  DEPARTMENT   OF  AGRICULTURE. 

In  this  campaign  of  education  the  Department  of  Agriculture  will 
cooperate  in  the  following  ways :  Copies  of  this  bulletin  or  of  other 
publications  of  this  Department  relating  to  the  bark  disease^  and  also 
typical  specimens  of  the  disease^  will  be  sent  to  any  person  applying 
for  them.  Two  specimens  will  be  sent  to  each  person — one  showing 
the  appearance  of  the  disease  on  smooth  bark,  and  the  other  the  later 
development  of  the  fungus  on  thick  bark.  In  both  these  specimens 
the  fungus  will  have  been  killed  by  soaking  in  formalin,  to  insure 
against  any  infection  from  this  source. 

So  far  as  the  supply  permits,  lantern  slides  and  photographs  will, 
upon  application,  be  loaned  for  special  lectures,  exhibits,  etc.,  to  the 
officers  of  States,  experiment  stations,  colleges,  and  schools  where 
agriculture  is  taught,  as  well  as  to  tree  wardens  and  other  officials 
whose  work  may  bear  directly  upon  local  campaigns  of  publicity. 

This  Department  will  always  examine  any  suspected  specimens  of 
this  disease  sent  to  Washington  by  mail,  and  will  report  the  findings 
as  promptly  as  possible.  Before  sending  specimens,  however,  all 
persons  are  urged  to  read  the  paragraphs  on  symptoms  on  pages  6  to 
9  in  order  to  select  the  specimens  intelligently.  For  example,  if  the 
end  of  a  girdled  and  withered  branch  is  sent,  it  is  not  possible  to  make 
a  dependable  diagnosis  unless  a  portion  of  the  girdling  area  happens 
to  be  included.  This  is  the  only  part  where  the  fungus  is  surely 
present,  and  the  fungus  itself  must  be  seen  in  order  to  be  absolutely 
sure  of  the  disease.  Portions  of  the  bark  that  show  the  small  orange 
or  reddish-brown  pustules,  about  the  size  of  the  heard  of  a  pin,  should 

467 


CONTROL   OP    THE    CHESTNUT   BAEK   DISEASE.  23 

always  be  sent,  if  these  can  be  found.    These  commonly  occur  near  the 
lower  edge  of  the  girdling  area. 

PUBLIC   COOPERATION. 

With  many  people  familiarized  with  the  appearance  of  the  chest- 
nut bark  disease  and  its  possibilities  of  harm,  the  disease  will  be 
noticed  and  stamped  out  by  private  effort  in  many  places  when  it 
first  appears  and  the  public  will  understand  and  be  ready  to  cooper- 
ate in  any  official  measures  of  control  as  soon  as  these  become  neces- 
sary in  any  locality. 

All  possible  forces  must  be  enlisted  in  a  campaign  of  publicity. 
The  cooperation  of  all  newspapers,  particularly  local  papers,  can  be 
easily  secured  in  all  the  States  where  the  chestnut  is  an  important 
tree.  A  portion  of  the  program  for  Arbor  Day,  1912,  should  be 
devoted  to  a  consideration  of  this  disease.  Teachers  of  nature  study, 
botany,  or  agriculture  in  the  public  schools  can  do  great  service  by 
teaching  their  pupils  how  to  recognize  the  disease  and  by  training 
them  to  be  on  the  lookout  for  its  first  appearance  in  the  home  com- 
munity. Such  a  body  as  the  "  Boy  Scouts  "  can,  if  properly  trained, 
become  in  every  community  a  most  efficient  force  for  locating  the 
disease.  The  boys  will  readily  appreciate  that  such  work  is  real 
"  scouting "  against  a  most  insidious  and  destructive  public  enemy. 
And,  finally,  many  private  owners  of  chestnut  trees  will  be  eager  to 
cooperate  with  the  State  authorities  in  the  early  elimination  of 
advance  infections  if  only  they  are  able  to  recognize  such  infections. 

THE   PROTECTION    OF   THE    SOUTHERN    STATES. 

It  must  be  remembered  that  the  bark  disease  has  as  yet  done  only  a 
small  fraction  of  the  damage  that  it  is  undoubtedly  capable  of  doing. 
The  best  chestnut  timber  of  America  is  south  of  the  Potomac  Eiver 
and  there  the  bark  disease  is  present  in  only  a  few  spots.  For  this 
reason  it  is  of  extraordinary  importance  that  these  few  spots  be  eradi- 
cated and  that  the  disease  be  soon  controlled  immediately  north  of 
the  Potomac.  If  the  bark  disease  once  becomes  well  established  in  the 
chestnut  forests  of  the  South,  it  will  be  well-nigh  impossible  to  control 
it,  on  account  of  the  sparsely  settled  and  mountainous  condition  of 
much  of  that  country  and  for  other  reasons  which  do  not  obtain 
farther  north. 

SUMMARY. 

(1)  The  chestnut  bark  disease  was  first  noted  near  New  York 
City  in  1904  and  is  now  present  in  at  least  10  States.  It  attacks  the 
American  chestnut,  the  European  chestnut,  the  chinquapin,  and, 
rarely,  the  Japanese  chestnut. 

(2)  The  total  financial  loss  from  this  disease  is  now  estimated  at 
$25,000,000. 

(3)  The  disease  is  caused  by  a  fungus,  and  the  entrance  of  a  spore 
at  any  point  where  the  bark  is  broken  may  cause  infection.     The 

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24  CONTROL,   OF    THE    CHESTNUT   BARK   DISEASE. 

disease  spreads  primarily  in  the  inner  bark  and  produces  character- 
istic lesions  which  girdle  the  tree  at  the  point  attacked. 

(4)  Conspicuous  symptoms  are  the  development  of  bunches  of 
sprouts  below  the  girdling  lesions;  the  half- formed  yellowish  leaves 
in  the  spring  on  the  previously  girdled  branches ;  the  reddish-brown 
leaves  on  branches  girdled  in  summer,  and  the  yellow,  orange,  or 
reddish-brown  pustules  of  the  fruiting  fungus  on  the  bark.  It  is 
practically  useless  to  attempt  systematic  location  of  the  disease  from 
October  to  April,  inclusive. 

(5)  The  spores  may  be  carried  considerable  distances  on  chestnut 
nursery  stock,  tan  bark,  and  unbarked  timber;  also  by  birds,  insects, 
squirrels,  etc.,  which  have  come  in  contact  with  the  sticky  spore 
masses.  Water  quickly  dissolves  these  spore  masses  and  the  minute 
spores  are  in  this  way  carried  along  with  water,  as,  for  instance,  with 
rain  water  running  down  a  tree.  Borers'  tunnels  form  the  most 
common  places  of  entrance  for  spores. 

(6)  The  only  known  practical  way  of  controlling  the  disease  in 
a  forest  is  to  locate  and  destroy  the  advance  infections  as  soon  as 
possible  after  they  appear  and,  if  the  disease  is  well  established  near 
by,  to  separate  the  area  of  complete  infection  from  the  comparatively 
uninfected  area  by  an  immune  zone.  Advance  infections  should  be 
located  by  trained  observers  and  destroyed  by  cutting  and  burning. 
As  the  disease  develops  almost  entirely  in  the  bark,  this  must  be  com- 
pletely destroyed  (burned). 

(7)  In  order  to  carry  out  the  above  methods  it  is  essential  that 
the  several  States  concerned  secure  necessary  legislation  and  appro- 
priations, following  the  example  of  Pennsylvania,  as  no  law  exists 
whereby  the  Federal  Government  can  undertake  such  work  and 
cooperation  among  private  owners  without  State  supervision  is 
impracticable. 

(8)  Chestnut  nursery  stock  should  be  rigidly  inspected  for  the 
disease  and  only  perfectly  healthy  plants  passed.- 

(9)  The  life  of  valuable  ornamental  trees  may  be  greatly  pro- 
longed by  promptly  cutting  out  all  diseased  areas  and  removing  all 
disease-girdled  branches  and  then  covering  the  cuts  with  tar.  Spray- 
ing is  of  no  use  in  stopping  the  fungus  after  it  has  once  started 
growth  in  the  bark. 

(10)  It  is  recommended  that  owners  of  infected  woodland  cut 
down  and  utilize  the  diseased  chestnut  timber  as  soon  as  possible. 

(11)  For  the  present  the  planting  of  chestnuts  anywhere  east  of 
Ohio  is  not  advised,  but  there  is  no  apparent  reason  why  chestnut 
orchards  west  of  Ohio  may  not  be  kept  free  from  the  disease. 

[A  list  giving  the  titles  of  all  Farmers'  Bulletins  available  for  distribution 
will  be  sent  free  upon  application  to  a  Member  of  Congress  or  the  Secretary  of 
Agriculture.] 
467 

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